Rocker arm for an internal combustion engine

ABSTRACT

A rocker arm (1) for the valve control of an internal combustion engine, in which the rocker arm is manufactured from stamped, deep drawn and subsequently heat treated, deep drawing sheet metal and characterized by the fact that the rocker arm (1) has opposite side pieces, in between a rolling element (10) is acommodated in a rotation position.

FIELD OF THE INVENTION

The invention relates to a rocker arm for valve control of an internalcombustion engine, where the valve lever is made from a punched,deep-drawn, and subsequently heat-treated deep-drawing metal sheet.

BACKGROUND OF THE INVENTION

Such rocker arms are known from the state of the art; they are generallyused as transmission elements in three types of engine controls, forpush-rod engines with the cam shaft on the bottom, for an overhead camshaft with the rocker arm as the direct transmission element between thecam shaft and the valve, and with tappet control, where the rocker armand the tappet form the transmission mechanism. In this connection,mechanical valve adjustment for sheet-metal rocker arms is performed atthe ball socket bearing, or at the rocker arm end, by means ofadjustment screws or eccentric elements. In this connection, the changein the lever ratio has a disadvantageous effect. Furthermore, the thumbrest on the valve-side end of the rocker arm, which is used in the stateof the art, has disadvantageous friction values, resulting in high wearfriction and wear of the valve guide, because of the lateral force ofthe valve shaft. In addition, in the case of the known, deep-drawnrocker arms, they must be additionally secured to prevent them fromtwisting, in order to stabilize the rocker arms around its longitudinalaxis. Such a rocker arm is described in DE 4024446 A1. Here, the rockerarm is mounted on a roller bearing, to keep it from twisting.

The present invention is therefore based on the problem (task) ofimproving the known, deep-drawn rocker arm known from the state of theart, and significantly reducing the valve guide wear and, at the sametime, simplifying production and making it more cost-effective.

This task is accomplished, according to the invention, by means of arocker arm made from a punched, deep drawn and subsequently heattreated, deep drawn sheet metal, and a roller element is mounted inslits inside parts which are open in the direction of a valve shaft.

In accordance with the invention, the rocker arm is structured in such away that it has opposite side parts, between which a roller element isheld so as to rotate.

Because of the low rolling friction on the valve shaft, its lateralforce on the valve guide is also reduced, and therefore the valve guidewear is significantly reduced. Furthermore, the rocker arm according tothe invention can be produced very cost-effectively, since onlydeep-drawing and punching processes, but no cutting work, are required.Heat treatment of the deep-drawn part subsequently takes place by meansof nitriding, carbonizing, or case-hardening. In the present case, valveadjustment takes place at the ball socket bearing, by means of a ballnut and a counter-bolt or counter-worm screw. Instead of the ball nut, asemi-cylindrical or cylindrical guide stone with a counter-nut can alsobe used. Furthermore, the invention provides that the roller element ismounted in slits in the side parts, which are open in the direction ofthe valve shaft. As a result, simple assembly is ensured, and additionallocking of the roller element in the bearing is unnecessary, since theroller element is held in place in the bearing by the counter-pressureof the valve tappet.

Furthermore, it is advantageous that the roller element is loosely heldin the slits. This ensures that it rotates easily, on the one hand, andthat it is easy to assemble, on the other hand.

A highly advantageous embodiment of the invention provides that sideguide parts are provided in the two end regions of the roller element,and that these extend beyond the valve shaft laterally. This preventstwisting of the rocker arm on the valve shaft, in surprisingly simplemanner, i.e. the valve shaft is stabilized around its longitudinal axis.In this connection, the side guide parts can be connected in one piecewith the roller element, i.e. project beyond its diameter, or can beseparate components. It is important here that the rocker movement ofthe rocker arm and the rolling movement of the roller element are nothampered.

Furthermore, an advantageous embodiment of the present inventionprovides that the side guide parts are arranged between the side partsand the roller element. This fixes the rocker arm and the valve shaft inplace, relative to one another, via the side guide parts.

Another advantageous embodiment provides that the side parts are guidedisks. This makes it possible to use mass-produced parts, which areinexpensively available.

Finally, it is a highly advantageous embodiment of the present inventionif the roller element has offset bearing ends. This reduces the numberof components and makes assembly and storage costs more advantageous.

The present invention will be explained in greater detail below, on thebasis of an exemplary embodiment, in connection with the attachedfigures. These show:

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 a lengthwise cross-section through a toggle lever of the typeaccording to the invention;

FIG. 2 a top view of a rocker arm according to FIG. 1;

FIG. 3 a cross-section through a rocker arm of the type according to theinvention in the installed state;

FIG. 4 detail IV from FIG. 3;

FIG. 5 a cross-section in the direction of the arrow V of the detail ofFIG. 4; and

FIG. 6 a three-dimensional partial view of the individual parts of arocker arm of the type according to the invention.

DETAILED DESCRIPTION

FIG. 1 shows a lengthwise cross-section through a rocker arm 1 with aspherical bearing bed 2, side part 3, band 18, guide disk 4, rollerelement bed 5, and tappet holder 6. Finally, the recesses 7, 8, and 9are evident in the deep-drawing metal sheet.

In this connection, the rocker arm 1 consists of a deep-drawing metalsheet, the contours and recesses of which are punched out. Subsequently,the deep-drawing metal sheet is formed, with the two side parts 3 beingbent perpendicular to the band 18, in order to reinforce the latter. Therecess 8 serves to hold the ball nut and the bearing bolt, and theroller element bed 5 serves to hold the roller element and the guidedisk 4. After forming, heat treatment takes place, in order to impartbetter strength characteristics and surface properties to the rockerarm.

FIG. 2 shows a top view of the rocker arm 1 of the type according to theinvention, where the same parts are identified with the same referencenumbers. In addition, FIG. 2 shows the roller element 10, which isarranged in the roller element bed 5, between the guide disks 4.

The rocker arm, which has been heat-treated by means of nitriding,carbonizing, or case-hardening, holds the roller element 10, which ismounted to rotate freely between the guide disks 4, in the rollerelement bed 5.

FIG. 3 shows a cross-section of the rocker arm according to FIG. 1 inthe installed state. In addition to the parts already described in FIG.1, the ball nut 11, a counter-bolt 12, a valve tappet 13, a valve 14, avalve spring 15, the housing 16, the bearing bolt 17, the valve guide19, and the valve seat 20 can be seen.

The tappet 13 is driven by way of the cam shaft, not shown; the formeris held in the tappet holder 6 with its end 21, which has asemi-spherical shape. By means of the up and down movement of the tappet13, the rocker arm 1 is rocked around the ball nut 11, which is held inthe spherical bearing bed 2. In this connection, the ball nut 11 isfixed in place on the bearing bolt 17. As a result of the togglemovement, the roller element, not shown, which is held in the rollerelement bed 5, presses on the valve shaft 22 of the valve 14. During thedownward movement, the spring 15 is compressed, and the roller elementrolls along the valve shaft 22. This causes the valve 14 to move out ofthe valve seat 20 and open. The upward movement of the rocker arm 1 issupported by the spring force of the spring 15. Furthermore, the rollerelement 10 is prevented from lifting off the valve tappet 13 in thisway. Because the roller element, not shown, again rolls on the valveshaft, there are practically no friction losses during the up and downmovement of the valve shaft.

FIG. 4 shows detail IV from FIG. 3, where the guide function of theguide disk 4, which surrounds the valve shaft 22 on both sides, isclearly evident. This prevents twisting of the rocker arm 1, and therocker arm is stabilized around its longitudinal axis.

FIG. 5 shows a cut-away view of the detail from FIG. 4 in the directionof the arrow V. Here the side walls 3 and the guide disks 4, as well asthe roller element 10 and the valve shaft 22 are evident. The rollerelement 10 is mounted to rotate freely in the roller element bed 5,being fitted into the roller element bed 5 in such a way that only avery small amount of play remains, because of the guide disks 4. Becausethe valve shaft 22 is held laterally between the guide disks 4, andbecause of the support function which results from this, twisting of therocker arm is effectively prevented.

FIG. 6 shows an exploded view of a rocker arm of the type according tothe invention, in which the side parts 3, the roller element bed 5, aswell as the roller element 10 with offset bearing ends 25 and the guidedisks 4 are shown.

During assembly, first the guide disks 4 are placed on the offsetbearing ends of the cylindrical roller element 10. Subsequently, theseparts are loosely inserted into the slit bearing 5 of the rocker arm 1.Because of the pressure on the valve tappet 13 resulting from the springforce of the spring 15, the roller element 10 is held in the rollerelement bed 5, together with the guide disks 4, preventing the rollerelement from lifting out of the bearing bed during operation.

I claim:
 1. Rocker arm (1) for valve control of an internal combustionengine, where the rocker arm (1) has opposite side parts (3), betweenwhich a roller element is held so as to rotate, when pressed on an upperend of a valve shaft (22) of a valve (14), wherein the rocker arm (1) ismade from a punched, deep-drawn and subsequently heat-treateddeep-drawing sheet metal, and that the roller element (10) is mounted inslits (5) in the side parts (3), which are open in the direction of thevalve shaft (22).
 2. Rocker arm according to claim 1, wherein the rollerelement (10) is loosely held in the slits (5).
 3. Rocker arm accordingto claim 1, wherein side guide parts are provided in the two end regionsof the roller element (10), which extend beyond the valve shaft (22)laterally.
 4. Rocker arm according to claim 3, wherein the side guideparts are arranged between the side parts (3) and the roller element(10).
 5. Rocker arm according to claim 4, wherein the side guide partsare guide disks (4).
 6. Rocker arm according to claim 1, wherein theroller element (10) is provided with bearing ends with reduceddiameters.